We plan to isolate and analyze zebra fish mutants with altered visual systems. Of particular interest initially will be mutants with altered organizations of retinal cell types, and specific enrichment procedures will be utilized to aid in the isolation of such mutants. The mutants will be analyzed by behavioral, anatomical, physiological and genetic methods. In order to increase the frequency of mutants in the populations subjected to selection, we will expose fish to mutagens at appropriate stages in their life cycle. Since most mutations are recessive, we plan to generate homozygous fish from mutagenized eggs in order to enable use to recognize mutant phenotypes. Procedures for generating homozygous fish, for mutagenizing, and for screening mutants with altered visual systems have already been developed in our laboratory.